In this note connections between root extensions of monoids and some finiteness conditions on monoids are studied, giving new proofs and generalizing results of Etingof, Malcolmson and Okoh for domains. In the same spirit, results of Jedrzejewicz and Zielinski on root-closed extensions of domains are generalized and sharpened to monoids. Using the same methods, a criterion for being a completely integrally closed domain is generalized to monoids.